In order to extend access to motor racing events and to reduce the costs thereof, there exists a need for a racing car having a size such that it can run on a track suitable for a conventional go-kart but which retains the appearance and characteristics of a conventional single seater formula car.
To produce a suitable vehicle for this purpose it is desirable that the following objectives are met to a broad extent:
1. The size of the vehicle is such that it can run on a track suitable for a go-kart i.e. the vehicle is small compared with a conventional single seater formula racing car; PA0 2. The vehicle is inexpensive to build and requires little maintenance; PA0 3. The vehicle has sufficient in-built strength to resist significant damage from average crashes encountered on a racing circuit; and PA0 4. The vehicle can be easily handled by a novice driver yet is challenging and exciting for the experienced driver. PA0 A. A space frame chassis with integral roll bar, similar to that of a typical conventional racing car but with its size restricted to able it to be raced on a larger outdoor go-kart track. A suitable car has an overall length in the range 2160 to 2760 millimeters and an overall width in the range 1335 to 1415 millimeters. PA0 B. A partially enclosed body similar to that of a formula car with an open cockpit for the driver. Preferably the chassis is formed from material comprising fibreglass particularly fibreglass strengthened with "KEVLAR" (RTM) strengthening agent. PA0 C. Seating for the driver which is suitable for an adult person in a reclined position similar to that of a formula one car, the seat being fitted with full racing harness. PA0 D. Larger tires of the size and kind now used in the racing class known as Mini Miglia--are either dry tires for dry conditions or wets for wet conditions suitable sizes being dry 180 mm R10s or wet 165 mm R10s. PA0 E. A rack and pinion steering mechanism similar to that used in formula one racing cars and which is recently beginning to be adopted in the more advanced go-karts, to give precise steering with maximum feel for the driver.
To meet these objectives a racing vehicle can be designed which has a space frame chassis similar to that of a conventional single seater formula car but which has restricted dimensions to enable it to be raced successfully on go-kart tracks such as those presently in use, in particular the larger outdoor go-kart tracks. The limited size of the chassis of the vehicle thus produced leads to a reduction in the space available within it for components and restricts further design modifications to the vehicle.
To produce a vehicle having a chassis of suitable restricted size, it is proposed in the present invention to design the vehicle without a differential on the rear axle and without a resilient suspension component on the rear and front axles.
The proposed design of the invention creates an inherent handling problem, in that the fixed rear axle without a differential resists turns and tends to proceed in a straight line thereby creating understeer or an inherent resistance to turning corners in the vehicle. The removal of the resilient suspension components and the increased weight in comparison to a go-kart increases the severity of the problem.
Steering systems are known such as the double wishbone type, generally comprising a hub carrier for rotatably supporting a front wheel, and upper and lower linkages for connecting upper and lower ends of the hub carrier to a vehicle body. According to such conventional wishbone arrangements, the kingpin axis about which the hub is carried and about which the wheel rotates, is theoretically fixed even during the steering operation. The camber characteristics of the vehicle are determined by the castor angle, i.e. the inclination of the kingpin axis to the longitudinal axis of the vehicle. The cornering performance during steering is primarily influenced by the cornering power of an outer front wheel, situated on an outer side with reference to a cornering centre. During steering the vehicle body rolls, which tends to increase the camber angle of the outer front wheel and hence the tyre inclination angle with reference to the ground surface in the positive camber direction, thereby lowering the cornering power of the outer front wheel. Vehicles incorporating such systems require full suspension systems if they are to operate effectively.